1. Field of the Invention
The present invention relates generally to energy efficient buildings and more specifically to a multi-vent for building roofs or walls, which removes humidity typically trapped in the walls, roof and insulation of the building.
2. Discussion of the Prior Art
A brochure MB304 published by the North American Insulation Manufacturers Association (NAIMA) continuously since 1991 describes the state of the art most typically used to insulate roofs and walls of pre-engineered metal buildings. This type of building currently represents over 40% of all non-residential buildings of two stories or less built in the US each year.
U.S. Pat. No. 4,446,664 to Harkins discloses a building insulation system. U.S. Pat. No. 4,573,298 to Harkins discloses a building insulation system. U.S. Pat. No. 5,953,875 of Harkins discloses a slide-in building insulation system. U.S. Pat. No. 6,247,298 to Harkins discloses a roof fabric dispensing device for insulation systems and air barriers over the exterior plane of the building structural members. U.S. Pat. No. 5,968,311 is a device for installing a vapor retarder over the purlins or joist to support insulation. U.S. Pat. No. 6,705,059 is a rolled fabric carriage device for unrolling a vapor retarding fabric over the tops of purlins, which is used to support insulation. U.S. Pat. No. 6,216,416 is a system for installing insulation over purlins. U.S. Pat. No. 5,921,057 is an apparatus for dispensing an insulation support sheet over the purlins. U.S. Pat. No. 5,653,081 is a method for paying out an insulation support sheet for insulating a building roof over the purlins. U.S. Pat. No. 4,222,212 is an insulated roof over the purlins. There are temporary buildings, which have a waterproof coverings over the tops of framing members to form a roof covering and which are commonly used for agricultural and storage purposes.
One common problem with the design of current buildings having integrated thermal insulation systems is the requirement for structural fastening of the insulation support apparatus through the plane of the insulation system. The “through-fastening” creates multiple thermal bridges, which reduces the building thermal performance up to fifty percent. The most predominant methods used to insulate pre-engineered metal buildings from as early as the 1950s, until today is simply draping the insulation over the exterior of the building structural members for support, applying the exterior building sheeting directly over the insulation and then applying the exterior sheeting attachment fasteners through the exterior sheeting, through the insulation from the exterior into the underlying building roof and wall structural members. This method results in thermal bridging fasteners with a frequency of about one fastener per every ten square feet of exterior surface area or less.
A second common problem is that insulation products in building roofs and walls are sandwiched between the roof or wall structural members and the overlying building exterior sheeting with compression of the insulation thickness and its inherent loss of thermal performance which results from this compression. Placing the roof and wall insulation tightly against the exterior roof and wall sheeting panels blocks the solar heat energy from being absorbed and radiated off the interior surface of the sheeting materials for any practical use. The solar energy that hits the building roof and wall surfaces is lost from any practical collection and use. At the same time, fossil fuel energy is purchased to provide heating, cooling and hot water heating for the building occupants and processes.
A third common problem of achieving energy efficient buildings is that the thermal insulation has traditionally been installed during the roof and wall sheeting process. Insulation methods which require the installation of fasteners from the interior during the integrated insulation and exterior sheeting process are shunned by installers of these materials in favor of methods that simply compress the insulation between the roof and wall structural members and the roof and wall sheeting panels with only externally applied fasteners. Such methods eliminate the need for fastening from the interior side of the roof and wall structure during the insulation and sheeting process and therefore are preferred by installers.
This practice severely limits the thermal performance of the buildings to much less than the desirable economic insulation levels. Due to the insulation thickness reductions and thermal bridging, building thermal performance is much less than what is required to honestly meet the minimum installed thermal performance criteria set forth by the various state energy codes. The most common building insulation methods not only compress the insulation thickness by variable percentages, but also thermally bridge the exterior conductive building sheeting surfaces to the interior exposed thermally conductive surfaces of the purlins, joists and girts. These structural configurations maximize the uncontrolled heat transfer between the two thermally bridged surfaces on the opposite sides of the thermal insulation layer and will frequently result in seasonal condensation on the interior exposed building structural members. The roof and wall structural members become very hot in the summer, when the heat is not wanted in the building interior conditioned space and are cold in the winter, when the heat is wanted in the building interior conditioned. Buildings that are thermally bridged between through the thermal insulation with exterior exposed conductive sheeting materials and interior exposed conductive roof purlins or joist and exposed conductive wall girts result in the opposite seasonal heat transfer effect that is desired and major loss of heating energy.
The cold exterior surface temperatures in the winter typically float up and down crossing over the dew point temperature of the interior conditioned air and also of the dew point temperature of the air trapped within the insulation of the roof and wall assemblies of the building. Fiberglass insulation is mostly air. This condition results in condensation of the water vapor that increases conductivity and reduces the insulation thermal performance, which may result in permanent building structural damage and may also interfere with the building use. If the condensed liquid water accumulates within the building roof and wall assemblies it may also result in dripping and damage to interior building contents.
Prior art like that disclosed in the Harkins U.S. Pat. No. 4,446,664 invention uses a steel strap support system, which temporarily spans across building bays with steel straps fastened at their ends and often installed in a woven mesh. A flexible sheet material is custom fabricated to fit the designated building areas, referred to as building bays, with the absolute minimum of field seams except along the building bay perimeter beams, where there is no problem sealing the edges as the workmen work on the top side of the rafter beams. The flexible sheet material is spread out and clamped in position on the platform of spanned support strapping and then fasteners are required to be installed through the steel straps and sheet material from the building interior into the inside flange of building roof purlins or joist from the interior. This method requires approximately one interior applied fastener for every 30 square feet of the building roof or wall structures. Each fastener is a thermal bridge between the steel strapping and the metal structure to which it is attached.
The invention of the U.S. Pat. No. 4,446,664 creates a defined space for insulation to expand, which eliminates virtually all unwanted compression of the insulation in the roof structures. This method also completely isolates all-of-the highly conductive metal roof and wall purlins or joist surfaces from direct contact with the interior conditioned air. This system however requires the installation of the fasteners from the interior of the building during the integrated process of installing the insulation and the sheeting of the building's exterior roof surfaces. The Harkins '664 patent, while much more thermally efficient than typical methods, is often avoided in favor of much less thermally efficient insulation products and methods which do not require fasteners to be installed from the building interior during the integrated roof insulation and exterior roof sheeting process.
Another problem that occurs in metal panel sheeted buildings is seasonal condensation problems in the wall and roof systems. This phenomenon becomes particularly evident with metal-sheeted buildings because the metal panel temperatures change almost instantly with a change in exterior temperatures. Typically, water vapor within the building interior conditioned space concentrates along with a natural heat gradient at the highest elevations within the building heated space. The concentration of water vapor in air is often measured and expressed as relative humidity. The warmer the air mixture is, the more the weight of water, in vapor form, it can hold. Water vapor will condense on any surface of the building structure it contacts, which is below its dew point temperature. The dew point temperature is the temperature at which the relative humidity of the air contacting the cooler surface will reach 100% relative humidity and begin depositing the excess water vapor as liquid water on that cooler surface. A similar phenomenon occurs within an air mixture itself as it cools and this condensation manifests itself as fog, dew, rain and other forms of precipitation.
In buildings, water vapor will migrate through the vapor retarders, through poorly sealed joints, through staple holes, through gaps, etc. and will condense on the interior surface of the exterior sheeting panels when the exterior surface temperatures are below the dew point temperature of the air mixture within the insulation space of the roof and wall assemblies of the building. The typical preferred insulation methods fill the roof and wall assemblies to the exterior sheeting and any moisture is trapped inside of the wall and roof assemblies. The moisture may condense and may accumulate seasonally during cold temperatures. This trapped water vapor and resultant liquid water will cause premature deterioration of the building roof and wall building components and will shorten the useful life of the building if it can't escape naturally. Many older metal buildings leak air or breathe through the eave and wall flashings and the unsealed wall panel joints due to wind pressure differences. This breathing allowed much of the trapped water vapor to escape, but at the expense of thermal insulation performance. New energy code requirements for sealing all construction joints will essentially eliminate this typical water vapor escape mechanism resulting in a much greater potential for condensation and accumulation of liquid water within these building roof and wall assemblies of the future.
Buildings that have the compressed thermal insulation, buildings that attempt to fill the roof and wall cavities, buildings that have thousands of staple holes along uniformly spaced insulation facing seams, buildings that have substantially thermally bridged conductive interior and exterior surfaces, buildings that trap and accumulate condensed water vapor within the insulated roof and wall assemblies, and buildings which repel the free solar heat energy hitting its exterior surfaces require significantly greater heating and cooling equipment capacities, require excessive fuel piping, require excessive electrical wiring, require excessive service capacities and cost significantly more to heat, cool and ventilate than would be required, if the above mentioned problems were solved.
Accordingly, there is a clearly felt need in the art for a building insulation system, which provides the following useful advantages:                That creates a defined space of sufficient air volume and distance between the roof and wall thermal insulation layer and the conductive exterior sheeting materials to achieve the economic insulation thickness and air gap space to operably manage the intrinsic air mixture, the air flows within and the collection of solar heat from the adjacent heat absorbing, conducting and radiating surfaces of the exterior building sheeting and of their thermally bridged roof purlins and wall girt structural members.        That creates a continuous insulation layer without having structural thermal bridging, nor having fasteners inserted through the insulation layer to support itself. An insulation layer that is supported completely from the interior side without the need for any fasteners installed from the interior during the integrated ceiling thermal insulation and exterior sheeting process of a building.        That provides for the natural collection and concentration of heat energy within defined air gap spaces created within the roof and wall assemblies, which heat can be actively collected from the defined spaces by one of several methods and used to reduce energy consumption for the building, its occupants and related processes.        That provides for water vapor control within the defined roof and wall assembly spaces to concentrate the water vapor by natural means and to actively remove and collect the water from the roof and wall defined air gap spaces as required to minimize any damaging accumulation and allow the simple collection and use of the clean water for various useful purposes.        That maximizes the absorption, collection and transfer of solar heat energy hitting the exterior surfaces of the building and to actively use the clean solar energy to reduce the consumption of purchased energy for the building interior space conditioning and related use processes. The colors and the emissivities of the roof and wall exterior sheeting panel surfaces can be selected to maximize solar energy absorption, transfer and use of the free solar energy, as opposed to reflecting it back into the external environment with it's value completely wasted, as is currently the predominant practice and also part of a growing trend known as “cool roofs” and highly reflective, “low emissivity” surface coating.        That use an active heat collection duct and piping systems installed at optimal locations within the defined air gap layers created within the walls and roof assemblies as a source for concentrated heat to be used directly with air circulation and/or indirectly through the use of a heat exchanger system such as a water pumping and storage system with fan-coil heat transfer units, baseboard type heating radiators, or the use of electric powered, refrigerant type of compressor driven electric heat pumps that collect heat from the pre-heated, pre-concentrated air within the solar wall and solar roof air gap layers in lieu of exterior unheated ambient air as a source for the heat energy it collects and transfers. Efficiencies of over 50 Btu's per watt are expected from this new solar heat pump building invention.        That would facilitate the collection, concentration and storage of the clean solar heat energy in water stored in insulated reservoirs for off peak demand use for space heating and hot water production processes. Excess heat energy collected can be used to melt snow and ice off roofs, driveways, sidewalks, etc. to eliminate typical removal costs, saving equipment costs, time and additional energy. The relatively clean water from snow and ice melting can also be collected, and recycled for many useful purposes.        That interconnects the wall solar energy air gap collection system to the roof solar energy air gap layer collection system which will facilitate the transfer of concentrated heat from the wall air gap layer to the roof air gap layer on demand. This heat transfer allows the building roof to be kept free of snow and ice by using solar heat energy collected in the wall air gap layer to maintain the solar exposed roof absorptive surface area exposed to direct solar energy to absorb the maximum solar energy possible.        That will use free solar heat from the solar wall collection system to eliminate ice damming on cold roof edges by keeping them free of ice accumulation caused by chronic build-up of ice from very slow melt of snow and ice off the exterior roof sheeting due to thermal bridging from the interior conditioned space and through the compressed thermal insulation.        That uses a subterranean air tubing and air conditioning system to pre-condition incoming ventilation air in all seasons to save energy and to also to simultaneously remove water vapor from warm, humid, incoming air during the summer cooling season, thereby reducing both the latent and sensible cooling loads required to maintain the interior conditioned space temperature and humidity at desired levels.        That simplifies the installation process and eliminates the requirement for any fastening from the interior of the building during the integrated process of installing the insulation support sheet material, the roof insulation and the exterior sheeting panels of the building roof.        That eliminates thermal bridging through the roof insulation to support the insulation layer.        That eliminates thermal bridging through the wall insulation layer for support of the insulation.        That reduces the need for energy for building environmental space conditioning to such a low level, that for practical investment payback reduces the building life cycle cost to a degree that renewable energy generation may be added to the building project so that it annually requires a net total of zero or less purchased energy for typical building conditioning and lighting loads, excluding other user loads, if any.        